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LTC3350 Recommended for New Designs
The LTC3350 is a backup power controller that can charge and monitor a series stack of one to four supercapacitors. The LTC3350’s synchronous step-down...
Datasheet
LTC3350 on Analog.com

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LTC3350_current sense



		

			

									
					    teli
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Jul 4, 2024 
				
			
			
		
    

				
		
    
		    		    
		    
		    		      		            		        
    Category: Datasheet/Specs
    
    		        		            		    
    Product Number:  LTC3350  
    
    		        		    		    	
			
    Hello
    

    I will use LTC3350.
    

    Datasheet P.21 and P.22 describes below equation about current sense of charge and peak inductor.
    

    I think that Ipeak is peak value.
    

    Is ICHG(MAX)  averaged value   or peak value ?　
    

    On the other words, does LTC3350 inculde the fitler circuit inside VCAP pin and ICAP pin or do we need to add external fitler circuit for VCAP and ICAP pin?
    

    

    

     
    

     
    

    

    Please let me know your advice.
    

    Regards,
    

    Teli
    
									
			        
		
    

				
						
        

    
    Tags: 
                                            
                 power management
                
                                                    
                 Datasheet/Specs
                
                                                    
                 Supercapacitor Chargers
                
                                                    
                 LTC3350
                
                                
            
    
    
    

		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    
















    
	
    
	
    
					



			


				
	









	
      
	

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      •  Analog Employees  
      
            
			                            
                                                                                                                        
            
				
			
            
					
      
	
      

		
		
      
					
      Hello, ICHG(MAX) is an average charge value. The LTC3350 will adjust the peak value up to 58mV/RSNSC (typ) to provide the average charge current of 32mV/RSNSC.
      

      IPEAK is the IPEAK current in boost mode. 
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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						in reply to MartyM
					
									
        
	
        

		
		
        
					
        MartyM
        

        

        Thank you for your answer.
        

        

        My understanding is that the LTC3350 does not filter the ripple internally to measure the average current, but rather adjusts the peak inductor current so that the average current will be  adjusted to 32mV/RSNSC.
        

        Is this correct?
        

        In that case, if I wants to measure the average current accurately, I think it would be better to add an RC filter externally to ICAP and VCAP to remove the ripple.
        

        

        Please let me know your advice.
        

        

        Regards,
        

        Teli
        

        
			
        

		
			
	      

		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
						
				
						
				
				
		
		
        
			
		
        
	
        

        

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													+1
							
			
				
									
							        
			
			
			
        •  Analog Employees  
        
            
			                            
                                                                                                                        
            
				
			
            
												
						in reply to teli
					
									
        
	
        

		
		
        
					
        When you are talking about measuring the current, are you talking about thru the internal ADC or some other means? The controller needs to look at the peak current for the control loop to work properly. This is different than the ADC measurements that samples the current for an ADC reading. If there is too big of a filter on ICAP and VCAP then the current limit will not function correctly. 
        
			
        

		
			
	      

		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
				
						
						
				
				
		
		
        
			
		
        
	
        

        

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